US Airways Captain Escorted from Aircraft
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An MEL must therefore contain fewer options than an MMEL and is presumably devised to take operational factors into account?
Ops factors are not taken into account (at least in the MELs I've seen) as each day will be different, limitations imposed by an INOP piece of equipment, though, are given.
From what I've read on this thread MEL's only specify single item failures and do not provide multiple-equipment-failure scenarios but can sometimes include provisions whereby one or more specifically identified items must be operative if a particular failed item is accepted?
Finally, from those with experience, can you advise whether it is common or rare to accept an aircraft with a double electrical failure or, specifically, a bus and APU fail?
I had posted early on in this thread that I had heard rumors of something else happening other than a simple gate return. Seems as though the CA may have in fact been acting less then cordially. Getting on the PA and "warning" passengers is not an intelligent move and it's not something I would do even if I declined a flight for technical reasons (though I only fly boxes at the moment). The fact is that most people are not experts on aviation matters and would react with fear and possibly refuse to fly on that specific aircraft for no other reason than someone said it's dangerous (even though it would be fixed in the mean time). Also, it's a pretty bad image to give to the flying public.
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Aviatorhi thanks for your response.
It strikes me that the multiple scenarios on offer when presented by a failure of more than one item on a MEL offers an ideal opportunity for the numerous combinations of dispatch possibilities to be calculated by computer.
In other words the aircraft manufacturer could develop software which allows crews to enter the defects and then provides answers as to whether the proposed combination of equipment failures are acceptable. The programme would probably prompt crew to confirm the serviceability of other critical or related items as well as to define aspects of the intended flight ie. flight time, over water etc.
Such a programme could help in standardising the dispatch criteria for each specific aircraft type in relation to the acceptable combinations of unserviceable equipment.
It strikes me that the multiple scenarios on offer when presented by a failure of more than one item on a MEL offers an ideal opportunity for the numerous combinations of dispatch possibilities to be calculated by computer.
In other words the aircraft manufacturer could develop software which allows crews to enter the defects and then provides answers as to whether the proposed combination of equipment failures are acceptable. The programme would probably prompt crew to confirm the serviceability of other critical or related items as well as to define aspects of the intended flight ie. flight time, over water etc.
Such a programme could help in standardising the dispatch criteria for each specific aircraft type in relation to the acceptable combinations of unserviceable equipment.
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Its possible that the APU issue may be a bit of a red herring here (i.e. not that important . Others have suggested MEL may permit this even on Etops flights)
BUT if any important electrical BUS is inoperative then that is a very big deal as it is quite likey that no electrical source whatsoever can be applied to that BUS, even if you had 10 back up generators.
I cannot imagine any MEL allowing dispatch with any important BUS inop. Others may be able to provide further specific information for this A330.
BUT if any important electrical BUS is inoperative then that is a very big deal as it is quite likey that no electrical source whatsoever can be applied to that BUS, even if you had 10 back up generators.
I cannot imagine any MEL allowing dispatch with any important BUS inop. Others may be able to provide further specific information for this A330.
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The discussion of hot battery bus reminds me of the MartinAir 767 back in 1996.
Event Details
The cause was simple enough, but grounds are the usually last thing looked at, and often overlooked, when troubleshooting.
Prior to departure, the flight crew noted anomalies with the airplane clocks. Once corrected, they proceeded with the flight. En route, the airplane experienced numerous electrical anomalies where various warning lights would illuminate, and then extinguish. These occurrences were also accompanied by uncommanded auto-pilot disconnects, changes in airplane zero fuel weight, as displayed on the control display unit (CDU) of the flight management system (FMS), and the blanking of transponder codes.
The cause was simple enough, but grounds are the usually last thing looked at, and often overlooked, when troubleshooting.
The investigation revealed that the negative cable for the main battery was not positively secured to the main battery shunt as a result of stripped threads found in the jam nut area on the stud. Additionally, the main battery shunt was not built up in accordance with Boeing specifications. An examination of other Boeing 767s in the Martinair fleet, and on the production line at Boeing revealed similar buildup problems with the battery shunt. Boeing personnel commented that a loose battery shunt may cause interruptions to the ground on the main battery bus of the airplane.
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Here is a link to another article that may shed some light on what led to the Captain being escorted away....
US Airways Captain Escorted From Airport - TheStreet
According to the article the plane sat at the gate with the passengers onboard with no A/C for roughly 5 hours before the captain chose to disembark them. The article speculates that her comments explaining the circumstances sparked her removal. Other possibility I see is if she "overrode" orders from operations the keep them (passengers) on the airplane...
US Airways Captain Escorted From Airport - TheStreet
According to the article the plane sat at the gate with the passengers onboard with no A/C for roughly 5 hours before the captain chose to disembark them. The article speculates that her comments explaining the circumstances sparked her removal. Other possibility I see is if she "overrode" orders from operations the keep them (passengers) on the airplane...
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Electrical Faults
As a licensed B1 Engineer on A320 and A330 a/c the MEL does not allow Dispatch for any ELEC BUS faults.
however, faults on the airbus show up and disappear all the time, especially on power-up and on starting engines, APU's etc; whenever high electrical loads are being consumed and also when the electrical power source supplying the ELEC busses is swapped from ground source, APU generator or engine generator.
These faults can appear/disappear due to the way the warnings are generated, the Airbus computers are constantly monitoring the A/C electrical systems and if a signal is lost for a specified length of time a fault message will appear and may disappear a second or two later when the signal is received, much the same as your laptop can do from time to time. Remember the airbus is primarily based on computer technology developed in the 1980's.
If a signal appears and then disappears it does not mean that there is a problem with that system, it could have been a momentary loss of one of it's many signal inputs, but it may indicate that there is an issue with this system and that some component/computer it may be indeed about to fail.
On the US Air issue, when the engine was selected to start the air pressure for the starter is supplied from the APU (which is already supplying the Electrical power to the A/C) the increase demand on the APU may have caused it to shut down, this is when the HOT BATT BUS should have supplied the A/C with power. the loss of the HOT BATT BUS may have been caused by the fact that it did not get time to kick in and supply the A/C and once the power was out that was it, lights out, literally!!!
the FACT that we don't have all the Facts means all of this is just coming from reading between the lines, when it comes to technical issues relating to modern aircraft we need to know exactly what happened, when, how and what were the warning signals generated as Airbus have a very detailed and specific Trouble Shooting Manual for finding the root cause of failures.
when the aircraft was brought back on stand and ground power supplied the fault was POSSIBLY not present and all tests may have had a SATIS result (total assumption based on experience with similar faults).
I have had strange failures occur on A/C that when tested have tested SATIS and have never returned. but serious consideration is needed when there are multiple MEL entries on failed components. The systems on these A/C are heavily dependent on signals from lots of other sensors, computers etc, having 2 or 3 concurrent computer problems as MEL entries is not a good idea as they may not seem to be interlinked but they may be.
As stated in previous posts The MEL is drafted by each operator based on the Manufacturer MMEL and must be more restrictive than the MMEL.
It does not take account of Multiple MEL items as it would be impossible to do, that decision is left with the Engineer approving the MEL entry/Deffered defect and the operators Maintenance control division whom the Approved engineer will have to discuss multiple MEL entries with, the operator's engineering department can get info from the manufacturer in relation to the consequences of specific multiple MEL/deffered defects/ U/S computers etc.
The Captain has the right to refuse the A/C if they feel that there has not been enough done to find the cause or the problem. We do not know what the subsequent flight crew's experienced either. Most airlines will back the captain up in such cases even if they are wrong, as safety is the primary consideration in aviation. to escort her with their corporate security is OTT to say the least as i believe she had a point.
But we really need ALL the facts before we condemn anyone whether it is the Flight crew, Management or Maintenance.
however, faults on the airbus show up and disappear all the time, especially on power-up and on starting engines, APU's etc; whenever high electrical loads are being consumed and also when the electrical power source supplying the ELEC busses is swapped from ground source, APU generator or engine generator.
These faults can appear/disappear due to the way the warnings are generated, the Airbus computers are constantly monitoring the A/C electrical systems and if a signal is lost for a specified length of time a fault message will appear and may disappear a second or two later when the signal is received, much the same as your laptop can do from time to time. Remember the airbus is primarily based on computer technology developed in the 1980's.
If a signal appears and then disappears it does not mean that there is a problem with that system, it could have been a momentary loss of one of it's many signal inputs, but it may indicate that there is an issue with this system and that some component/computer it may be indeed about to fail.
On the US Air issue, when the engine was selected to start the air pressure for the starter is supplied from the APU (which is already supplying the Electrical power to the A/C) the increase demand on the APU may have caused it to shut down, this is when the HOT BATT BUS should have supplied the A/C with power. the loss of the HOT BATT BUS may have been caused by the fact that it did not get time to kick in and supply the A/C and once the power was out that was it, lights out, literally!!!
the FACT that we don't have all the Facts means all of this is just coming from reading between the lines, when it comes to technical issues relating to modern aircraft we need to know exactly what happened, when, how and what were the warning signals generated as Airbus have a very detailed and specific Trouble Shooting Manual for finding the root cause of failures.
when the aircraft was brought back on stand and ground power supplied the fault was POSSIBLY not present and all tests may have had a SATIS result (total assumption based on experience with similar faults).
I have had strange failures occur on A/C that when tested have tested SATIS and have never returned. but serious consideration is needed when there are multiple MEL entries on failed components. The systems on these A/C are heavily dependent on signals from lots of other sensors, computers etc, having 2 or 3 concurrent computer problems as MEL entries is not a good idea as they may not seem to be interlinked but they may be.
As stated in previous posts The MEL is drafted by each operator based on the Manufacturer MMEL and must be more restrictive than the MMEL.
It does not take account of Multiple MEL items as it would be impossible to do, that decision is left with the Engineer approving the MEL entry/Deffered defect and the operators Maintenance control division whom the Approved engineer will have to discuss multiple MEL entries with, the operator's engineering department can get info from the manufacturer in relation to the consequences of specific multiple MEL/deffered defects/ U/S computers etc.
The Captain has the right to refuse the A/C if they feel that there has not been enough done to find the cause or the problem. We do not know what the subsequent flight crew's experienced either. Most airlines will back the captain up in such cases even if they are wrong, as safety is the primary consideration in aviation. to escort her with their corporate security is OTT to say the least as i believe she had a point.
But we really need ALL the facts before we condemn anyone whether it is the Flight crew, Management or Maintenance.
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however, faults on the airbus show up and disappear all the time,
hetfield
Busdriver since 1989 on A300, 320 family and 340
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AirbusMech
Thank you for that very comprehensive explanation. I am reasonably familiar with most of what you say and have seen plenty of such examples as you suggest.
As you say the lack of actual detail of this particular incident renders everything up until now just speculation. But I am sure you will agree that for most of the "transient" or appparent faults you list, these would normally be very easily rectifiable by the crew or engineers with simple resets or even the the BIG reboot-all power OFF then ON again. Additionally, if the crew were familiar with the Airbus to any degree (and I am assuming these were) then they too would have encountered many of the scenarios you describe and the reasons behind them.
At face value, it would be difficult for most people to accept that any management could possibly try to pressurise crews into accepting an aircraft in the condition alleged so far. HOWEVER one only has to read John Warham's book on the Cathay 49ers Fragrant Harbour-pprune to see what some managers are truly capable of, albeit in different ways.
As you say the lack of actual detail of this particular incident renders everything up until now just speculation. But I am sure you will agree that for most of the "transient" or appparent faults you list, these would normally be very easily rectifiable by the crew or engineers with simple resets or even the the BIG reboot-all power OFF then ON again. Additionally, if the crew were familiar with the Airbus to any degree (and I am assuming these were) then they too would have encountered many of the scenarios you describe and the reasons behind them.
At face value, it would be difficult for most people to accept that any management could possibly try to pressurise crews into accepting an aircraft in the condition alleged so far. HOWEVER one only has to read John Warham's book on the Cathay 49ers Fragrant Harbour-pprune to see what some managers are truly capable of, albeit in different ways.
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Post #71, by a USAIR pilot. Said he doesn't have the facts. I'm curious, if a pilot for the company/union acknowledges he doesn't have all the facts why do people, who's only knowledge is the news reports(wow, that's a 100% reliable source) or the internet (better than 100%) just accept one side of the story?
I highly doubt the company was trying to force them to fly the airplane with the cockpit not "having any electirical power" as reported by a union spokesman. The FAA would be all over that.
And the whole, what did she, or didnt' she, say over the PA? Couple hundred witnesses maybe? Any eyewitness reports? None.
You guys have the cart a couple of counties ahead of the horse. Wait for facts? Why? Writing history from thousands of miles away is more fun!
I highly doubt the company was trying to force them to fly the airplane with the cockpit not "having any electirical power" as reported by a union spokesman. The FAA would be all over that.
And the whole, what did she, or didnt' she, say over the PA? Couple hundred witnesses maybe? Any eyewitness reports? None.
You guys have the cart a couple of counties ahead of the horse. Wait for facts? Why? Writing history from thousands of miles away is more fun!
It strikes me that the multiple scenarios on offer when presented by a failure of more than one item on a MEL offers an ideal opportunity for the numerous combinations of dispatch possibilities to be calculated by computer.
In other words the aircraft manufacturer could develop software which allows crews to enter the defects and then provides answers as to whether the proposed combination of equipment failures are acceptable. The programme would probably prompt crew to confirm the serviceability of other critical or related items as well as to define aspects of the intended flight ie. flight time, over water etc.
Such a programme could help in standardising the dispatch criteria for each specific aircraft type in relation to the acceptable combinations of unserviceable equipment.
In other words the aircraft manufacturer could develop software which allows crews to enter the defects and then provides answers as to whether the proposed combination of equipment failures are acceptable. The programme would probably prompt crew to confirm the serviceability of other critical or related items as well as to define aspects of the intended flight ie. flight time, over water etc.
Such a programme could help in standardising the dispatch criteria for each specific aircraft type in relation to the acceptable combinations of unserviceable equipment.
NOT!
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I was pax on the same airline on am 330 ex CLT yesterday evening that had no APU, got fairly uncomfortable at the gate in Charlotte (left about 50 minutes late). Also a 90 minute stop was required in PHL 'for technical reasons' (I assume to rectify a MEL item before a transatlantic flight) but I felt everything was done by the book and the crew were excellent, if a little in the dark as to the details themselves. It only cost a couple of hours, in all.
Safety first.
Safety first.
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It strikes me that the multiple scenarios on offer when presented by a failure of more than one item on a MEL offers an ideal opportunity for the numerous combinations of dispatch possibilities to be calculated by computer.
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Has is been confirmed that she did this?
Perhaps it is wiser to focus on eliminating the faults occuring rather than building solutions to accomodate them.
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I think you will find that with no APU on an ETOPS flight is a 'deal breaker'
Person Of Interest
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Earl...you keep repeating your common theme..."but isn't there some way that???"...
You've been answered many times previously on this thread...IT'S THE CAPT'S DECISION, PERIOD!!!...regardless of what the MEL says...
Myself, I wouldn't fly any Boeing, Airbus, etal, across the ocean, Andes or anywhere else remotely similar with any dodgy electricial squawks...If the D/O wants me to fly it from MIA to ORD, well, that's another story...
Just because it's "LEGAL" doesn't mean it's either prudent or SAFE!!!
You've been answered many times previously on this thread...IT'S THE CAPT'S DECISION, PERIOD!!!...regardless of what the MEL says...
Myself, I wouldn't fly any Boeing, Airbus, etal, across the ocean, Andes or anywhere else remotely similar with any dodgy electricial squawks...If the D/O wants me to fly it from MIA to ORD, well, that's another story...
Just because it's "LEGAL" doesn't mean it's either prudent or SAFE!!!